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Old Jan 2, 2013, 06:03 PM   #1
bradl
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iMac as a second monitor?

I was thinking about this, as I'm looking to go more legit than the hackintosh I put together for my desktop machine, as well as the MBA that I have.

The only thing really keeping me tied to anything with a PC is flightsimming and realtime ATC over a network, and because of that, I prefer to use a second monitor when I use my PC.

However, lately I have had this penchant for decluttering, and am looking to get rid of a lot of my hardware (I dropped my two ATX Mid-towers that were running Linux and Windows for 2 miniITX builds running Mountain Lion and Windows, though that still leaves me with 2 boxes on my desk). Wile I love the Hackintosh, I'm also growing tired of rolling my own builds (that's so 1990s/2000s), to where I want easy and simple to maintain. So I'm thinking iMac now. Business there, simming on the PC.

But that still leaves the problem of the 2nd monitor, as I don't want 3 monitors on my desk. Looking at the specs of the iMac, I noticed that while it has a discrete video card, it also has a miniDisplay port.

My question: Would it be possible to connect a MiniDisplay cable between a high powered card (say, an AMD Radeon HD 6950) and the back of an iMac to use the iMac as a second monitor? I would assume you could, but that is without knowing how it would switch between the discrete display and the miniDisplay port. So would this be possible?

BL.
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Old Jan 2, 2013, 06:33 PM   #2
BSoares
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If it's a 2011 or 2012 iMac then only Thunderbolt sources work. If it's late 2009 or 2010 then Mini DisplayPort works but can be picky sometimes.
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Old Jan 2, 2013, 07:18 PM   #3
bradl
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Originally Posted by BSoares View Post
If it's a 2011 or 2012 iMac then only Thunderbolt sources work. If it's late 2009 or 2010 then Mini DisplayPort works but can be picky sometimes.
But that's the confusing part. On Apple's site, they have this listed:

Connections and Expansion
  • SDXC card slot
  • Four USB 3 ports
  • Two Thunderbolt ports
  • Mini DisplayPort output with support for DVI, VGA and dual-link DVI (adapters sold separately)
  • 10/100/1000BASE-T Gigabit Ethernet (RJ-45 connector)
  • Kensington lock slot

http://store.apple.com/us/browse/hom...ac/family/imac

This leads to the assumption that Mini DisplayPort is either native, or supported through Thunderbolt, otherwise it wouldn't be mentioned at all, and this is on the 2012 iMac, both 21" and 27" variants..

BL.
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Old Jan 2, 2013, 07:40 PM   #4
Tankmaze
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if you use a macbook pro and wanted the imac as the external screen, you can connect with mini display or thunderbolt cable and press F2 to use the imac screen.

but I don't know how to use it with PC
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Old Jan 2, 2013, 07:56 PM   #5
Stetrain
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Originally Posted by bradl View Post
But that's the confusing part. On Apple's site, they have this listed:

---

This leads to the assumption that Mini DisplayPort is either native, or supported through Thunderbolt, otherwise it wouldn't be mentioned at all, and this is on the 2012 iMac, both 21" and 27" variants..

BL.
That's for video output, not video input.

The iMac can output video via Mini-Displayport or Thunderbolt, and in addition it can accept video input via Thunderbolt.
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Old Jan 2, 2013, 09:05 PM   #6
Arman
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Thunderbolt is backward compatible with mini display port. They are the same connection. Yeah read more closely. That is for output not input. There are a few motherboards coming out with thunderbolt and potentially Mac compatible. Can't say for sure.

This article may help.

http://m.cnet.com/news/confusing-mini-displayport-with-thunderbolt/20043524
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Old Jan 10, 2013, 05:02 PM   #7
bradl
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Revisiting this, as I just came back home from a visit to the Infinite Loop.

You indeed *can* use your late 2012 iMac as a second input monitor to a PC, if the PC's video card supports Mini DisplayPort. They stated that it was so because Thunderbolt is not only backwards compatible with Mini DisplayPort (as we all know), but also because Thunderbolt is bi-directional, so that port could be used for output as well as input from another Thunderbolt device or Mini DisplayPort card.

Now knowing this, I'm seriously thinking about the iMac.

BL.
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Old Jan 10, 2013, 05:07 PM   #8
Katori
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Originally Posted by bradl View Post
Revisiting this, as I just came back home from a visit to the Infinite Loop.

You indeed *can* use your late 2012 iMac as a second input monitor to a PC, if the PC's video card supports Mini DisplayPort. They stated that it was so because Thunderbolt is not only backwards compatible with Mini DisplayPort (as we all know), but also because Thunderbolt is bi-directional, so that port could be used for output as well as input from another Thunderbolt device or Mini DisplayPort card.

Now knowing this, I'm seriously thinking about the iMac.

BL.
Are you sure? I was almost positive that only Tbolt-equipped PCs could use Target Display Mode.
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Old Jan 10, 2013, 05:21 PM   #9
bradl
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Originally Posted by Katori View Post
Are you sure? I was almost positive that only Tbolt-equipped PCs could use Target Display Mode.
According to them, yes. Because of the port being bi-directional, it could accept input from another Thunderbolt device, and by nature of it being backwards compatible with Mini DisplayPort, another Mini DisplayPort card.

I'm waiting for a friend's 21.5" to come in so I could try it with my PC. If it works, I'm sold.

BL.
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Old Jan 10, 2013, 05:27 PM   #10
Jiggly Billy
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Originally Posted by bradl View Post
According to them, yes. Because of the port being bi-directional, it could accept input from another Thunderbolt device, and by nature of it being backwards compatible with Mini DisplayPort, another Mini DisplayPort card.

I'm waiting for a friend's 21.5" to come in so I could try it with my PC. If it works, I'm sold.

BL.
Apple states that it will only work when both devices have Thunderbolt, and a Thunderbolt to Thunderbolt cable is used.

http://www.apple.com/imac/specs/

Listed under Video
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Old Jan 10, 2013, 05:34 PM   #11
bradl
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Originally Posted by Jiggly Billy View Post
Apple states that it will only work when both devices have Thunderbolt, and a Thunderbolt to Thunderbolt cable is used.

http://www.apple.com/imac/specs/

Listed under Video
And what I am saying is that the techs down at their HQ are saying that it will work with mini DisplayPort, due to the Thunderbolt port being backwards compatible and bi-directional. Otherwise, they wouldn't be offering the ability to use mini DisplayPort as output nor input. I specifically asked that question.

BL.
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Old Jan 10, 2013, 05:38 PM   #12
Stetrain
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Originally Posted by bradl View Post
And what I am saying is that the techs down at their HQ are saying that it will work with mini DisplayPort, due to the Thunderbolt port being backwards compatible and bi-directional. Otherwise, they wouldn't be offering the ability to use mini DisplayPort as output nor input. I specifically asked that question.

BL.
In that case the same would be true of the 2011 iMacs, which have Thunderbolt video ports as well, but it isn't. The 2011 iMacs are know for sure to only accept video input from a Thunderbolt device, and I haven't seen any evidence that the 2012 models are any different.

Quote:
iMac (21.5-inch, Mid 2011) and iMac (27-inch, Mid 2011) and later computers support Target Display Mode via Thunderbolt to Thunderbolt cable (2 m) when the source is another Thunderbolt-equipped computer.

iMac (27-inch, Mid 2011) computers do not support Target Display Mode via Mini DisplayPort cables.
http://support.apple.com/kb/TS3775

Who was telling you otherwise? A Genius at an Apple Store? They aren't always correct.
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Old Jan 10, 2013, 05:55 PM   #13
vooblu
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Are you sure they understood you correctly?

You can use a mini displayport cable on your iMac, but only for video-out (ie. if you want to use another monitor as a second screen for your mac).

If you want to use your iMac as a PC monitor, you must use a thunderbolt cable and it only works from thunderbolt > thunderbolt port.

While I'm very confident it won't work, I can try this for you when my mac comes next week. I plan on using the iMac as a PC screen, but my PC motherboard has a thunderbolt connection, so technically I should be fine (another macrumors member confirmed it works with TB PC's).
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Old Jan 10, 2013, 06:05 PM   #14
bradl
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Originally Posted by Stetrain View Post
In that case the same would be true of the 2011 iMacs, which have Thunderbolt video ports as well, but it isn't. The 2011 iMacs are know for sure to only accept video input from a Thunderbolt device, and I haven't seen any evidence that the 2012 models are any different.


http://support.apple.com/kb/TS3775

Who was telling you otherwise? A Genius at an Apple Store? They aren't always correct.
As I mentioned, I just got back home to Sacramento from a work-related trip to Cupertino. I stopped at Apple's campus. It was the techs there that mentioned this.
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Old Jan 10, 2013, 06:52 PM   #15
TheyCallMeBT
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It works from a MDP out on my PC's graphics card to the MDP on the back of my iMac. But note that my iMac is a mid 2010 model, which was before Thunderbolt came out.

I was curious if anyone knew if this functionality works correctly in Mountain Lion with this model iMac??
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Old Jan 19, 2013, 05:47 AM   #16
mcfly2
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It works from a MDP out on my PC's graphics card to the MDP on the back of my iMac. But note that my iMac is a mid 2010 model, which was before Thunderbolt came out.

I was curious if anyone knew if this functionality works correctly in Mountain Lion with this model iMac??
Yes, I use my mid-2010 iMac with Mtn Lion as an external display for my W8 PC, via displayport to mini-displayport.
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Old Jan 22, 2013, 10:59 PM   #17
TheyCallMeBT
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Yes, I use my mid-2010 iMac with Mtn Lion as an external display for my W8 PC, via displayport to mini-displayport.
Thank you so much! It's been very difficult to get an answer to this, you're the first. So you're on the most up to date version of Mtn Lion and your brightness controls, volume/ music controls, and Fn + F2 all work, right?

Thanks!!
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Old Jan 23, 2013, 09:15 AM   #18
mcfly2
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Thank you so much! It's been very difficult to get an answer to this, you're the first. So you're on the most up to date version of Mtn Lion and your brightness controls, volume/ music controls, and Fn + F2 all work, right?

Thanks!!
Yep, everything works. Though every time I switch between iMac and PC I have to readjust the brightness. Which isn't so bad considering back when I first started doing this, the iMac would come on full brightness and there was no way to adjust it.
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Old Jan 23, 2013, 08:16 PM   #19
TheyCallMeBT
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Yep, everything works. Though every time I switch between iMac and PC I have to readjust the brightness. Which isn't so bad considering back when I first started doing this, the iMac would come on full brightness and there was no way to adjust it.
Yeah, I had read that one somewhere. That's not an issue at all. I would likely adjust it any way. Well as soon as I can fully transition out of FCP7 into Premiere (just to be safe in case there is an issue with FCP), I'll update to ML. I'll give it a go on my laptop first. Thank you again!!!
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Old Feb 13, 2013, 09:44 AM   #20
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Originally Posted by mcfly2 View Post
Yes, I use my mid-2010 iMac with Mtn Lion as an external display for my W8 PC, via displayport to mini-displayport.
I just wanted to know if I understood this right.

You have PC connected with iMac as PCs only screen? So no other screens? Just the iMac.

You connected PCs video card with iMac using Mini Displayport cable?

So can you have OSX and Windows running at the same time? OSX in iMac and Windows in PC. How do you switch between the two on-the-fly if this is possible.

Can you somehow use iMac as monitor only so that you wouldn't actually launch OSX etc. Can you use it to just show the picture coming from another computer?
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Old Feb 13, 2013, 11:06 AM   #21
mcfly2
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Originally Posted by Nihilius View Post
You have PC connected with iMac as PCs only screen? So no other screens? Just the iMac.
I've run with multiple monitors and with the iMac being the only monitor. Either case works fine.

Quote:
Originally Posted by Nihilius View Post
You connected PCs video card with iMac using Mini Displayport cable?
My PC has a Displayport output. I connect the iMac via a Displayport to Mini Displayport cable, which I purchased on Amazon for around $10.

Quote:
Originally Posted by Nihilius View Post
So can you have OSX and Windows running at the same time? OSX in iMac and Windows in PC. How do you switch between the two on-the-fly if this is possible.
Yes, OSX and Windows at the same time. You switch between the them via Cmd-F2 keypress on the iMac keyboard.

Quote:
Originally Posted by Nihilius View Post
Can you somehow use iMac as monitor only so that you wouldn't actually launch OSX etc. Can you use it to just show the picture coming from another computer?
As far as I know, you have to have OSX running in order to use the iMac as an external display. I never could find a way to do it without running OSX.

Be aware! I can vouch for this working on a mid-2010 iMac, which is the model just before they came out with Thunderbolt. I don't know if this works on newer iMacs with Thunderbolt.

Last edited by mcfly2; Feb 13, 2013 at 11:11 AM. Reason: additional info
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Old Feb 13, 2013, 11:16 AM   #22
Nihilius
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Thanks!

You said your PC has Displayport out. Is it in your motherboard or video card? Probably doesn't matter but I just want to make sure.

I have Mid-2011 iMac which does have Thunderbolt. Does anyone have idea I can have the same setup running on my machine?
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Old Feb 13, 2013, 11:27 AM   #23
mcfly2
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Originally Posted by Nihilius View Post
Thanks!

You said your PC has Displayport out. Is it in your motherboard or video card? Probably doesn't matter but I just want to make sure.

I have Mid-2011 iMac which does have Thunderbolt. Does anyone have idea I can have the same setup running on my machine?
I'll double-check when I get home, but pretty sure the Displayport output is on a separate video card.

When I bought the iMac I had the option of the older 2010, or the newer 2011. At the time, I had read that Thunderbolt iMacs required Thunderbolt outputs to be used as an external display. This is why I went with the 2010. I don't know if this has changed, but my guess it that it's still true, and that you won't be able to use a Thunderbolt iMac as an external display using a Displayport output. See here: https://discussions.apple.com/thread...art=0&tstart=0
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Old Feb 13, 2013, 11:35 AM   #24
Nihilius
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Okay, I did some research and it seems that starting from mid-2011 iMacs you can only use iMac as monitor if the source has Thunderbolt output.

It seems there are some motherboards which have Thunderbolt like. For example:

http://www.pcper.com/reviews/Motherb...erboard-Review

I don't know much about technical stuff so here's a stupid question. If I connect my iMac as monitor to PC equipped with that MSI mobo can I still utilize the power of my separate internal GPU in that same PC?
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Old Dec 7, 2013, 10:23 AM   #25
oranical
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Hi there I've been trying to find out if i can use my imac (27" late 2011) as a external display for my PC-Gigabyte A75m-d2h motherboard- (that does not have thunderbolt port but has a VGA out).
================
My computer has a Mini DisplayPort and i purchased a Mini DisplayPort To VGA Adapter and i connected the vga cable to my the back of my PC. My imac interpreted the input from my pc as a external monitor. i can't find out how to switch that so my imac is a monitor.

THank you.
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